Cementing compositions including salts

ABSTRACT

Disulfonate salts of 2,4-pentanedione and methods for making such salts are described. The disulfonate salts are useful as cement dispersants. Cement compositions including such salts, methods for making cement compositions including such salts, and methods for performing cementing operations using such cement compositions are also described.

BACKGROUND

The present disclosure relates generally to salts that are useful ascement dispersants, methods for making such salts, cement compositionsincorporating such salts, and methods for cementing using cementcompositions incorporating such salts. In particular, a disulfonate saltof 2,4-pentanedione and methods for making and using such a salt aredescribed.

Cement dispersants are often used in cement compositions utilized inconstruction for facilitating the mixing of the cement compositions.Also, in the cementing of oil and gas wells and the like, dispersantsare extensively used to reduce the apparent viscosities of the cementcompositions utilized. The reduction of the apparent viscosity of acement composition allows the cement composition to be pumped with lessfriction pressure and less pump horsepower. In addition, the lowerapparent viscosity often allows the cement composition to be pumped inturbulent flow. Turbulent flow characteristics are desirable whenpumping cement compositions in oil and gas wells to more efficientlyremove drilling fluid from surfaces in the well bore as the drillingfluid is displaced by the cement composition being pumped. The inclusionof dispersants in cement compositions is also desirable in that thepresence of the dispersants reduces the water required for preparationof the cement compositions. Cement compositions having a reduced watercontent are characterized by improved compressive strength development.

A number of dispersing agents have been utilized heretofore in cementcompositions, particularly in cement compositions used for primary andremedial cementing in oil and gas wells. For example, certain organicacids, such as gluconic acid and citric acid, have been used as cementdispersants. However, such organic acids are also strong set retardingagents. That is, the presence of an organic acid dispersant in a cementcomposition prevents the cement composition from setting for arelatively long period of time. Such a delayed set is often costly orotherwise detrimental. Other dispersants that are commonly used inhydraulic cement compositions include polynapthalene sulfonate,poly-B-naphthol sulfonate, polymelamine sulfonate, and many others.While such dispersants function very well in cement compositions, theycan be environmentally unacceptable, especially in offshore operationswhere particular ecological properties may be required.

DESCRIPTION

According to embodiments described herein, a method of cementing isprovided. The method includes introducing a cement compositioncomprising cementitious material, mixing fluid and a disulfonate salt of2,4-pentanedione into an area to be cemented, and allowing the cementcomposition to set therein. In certain embodiments, the 2,4-pentanedionedisulfonate salt acts as a cement dispersant. According to certainembodiments, the area to be cemented is in a subterranean zone, whichmay be penetrated by a well bore.

According to other embodiments described herein, methods of preparing adisulfonate salt of 2,4-pentanedione are provided. According to one suchmethod, 2,4-pentanedione is sulfonated by reacting it with a sulfursource, for example, chlorosulfonic acid. The molar ratio of the sulfursource to 2,4-pentanedione is in the range of from about 4:1 to about1:1 in some embodiments, in the range of from about 3:1 to about 2:1 inother embodiments, or in the range of from about 3.5:1 to about 2.5:1 instill other embodiments. The resulting product includes2,4-pentanedione-1,5-disulfonic acid, and other acid by-products, suchas hydrochloric and sulfuric acids, and/or mono-sulfonic acids.

The resulting product is then reacted with a base, for example, sodiumhydroxide, to neutralize the 2,4-pentanedione-1,5-disulfonic acid,thereby forming a salt of 2,4-pentanedione. The amount of base reactedwith the resulting product is that amount that will neutralize at leasta portion of the 2,4-pentanedione-1,5-disulfonic acid. In certainembodiments, the base is added until the resulting product isneutralized to a pH of about 7. Any other acids, such as hydrochloric,sulfuric, or mono-sulfonic acids that may be present as by-products, mayalso be neutralized by reaction with the base.

The neutralized product is then rinsed with a rinsing agent, forexample, methanol, to remove other acid by-products, such ashydrochloric and sulfuric acids, and/or mono-sulfonic acids, and/or toremove other salts formed by the neutralization, such as salts ofhydrochloric and sulfuric acids, and/or mono-sulfonic acids. It wasdiscovered that hydrophobic solvents, such as methanol, would remove theby-product acids and/or salts, while leaving the salt of2,4-pentanedione-1,5 disulfonic acid primarily undissolved.

According to other examples, the rinsing agent can be anotherhydrophobic solvent such as ethanol, or can be a polar solvent such asdimethylformamide (“DMF”), or can be any other solvent that will removeor dissolve the by-products, and not the disulfonate salt.

According to some exemplary methods for preparing a disulfonate salt of2,4-pentanedione, the reaction of 2,4-pentanedione with a sulfur sourceis conducted in an inert solvent. The reaction solvent can bechloroform, or a halogenated hydrocarbon such as carbon tetrachloride,1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethaneand 1,1,2,2-tetrachloroethane.

According to other embodiments for preparing a disulfonate salt of2,4-pentanedione, the reaction of 2,4-pentanedione with a sulfur sourceis conducted without a solvent. In still other examples, the reactionoccurs in an inert atmosphere. According to one such example, the inertatmosphere comprises nitrogen.

According to some exemplary methods for preparing a disulfonate salt of2,4-pentanedione, the base that is reacted with the reaction product of2,4-pentanedione and a sulfur source comprises an alkali metal or analkaline earth metal. According to one example of such methods, the baseis sodium hydroxide, and the neutralization reaction results in theformation of 2,4-pentanedione-1,5-sodium disulfonate, and may alsoresult in other salts from acid by-products that may have been present.According to other embodiments, a potassium salt, a magnesium salt, abarium salt, an ammonium salt, a calcium salt or a cesium salt of2,4-pentanedione is prepared by reacting the reaction product of2,4-pentanedione and a sulfur source with a base derived from potassium,magnesium, barium, ammonium, calcium or cesium. Suitable sources includebut are not limited to hydroxides of potassium, magnesium, barium,ammonium, calcium and cesium. The resulting salts would include2,4-pentanedione-1,5-potassium disulfonate;2,4-pentanedione-1,5-magnesium disulfonate; 2,4-pentanedione-1,5-bariumdisulfonate; 2,4-pentanedione-1 ,5-ammonium disulfonate;2,4-pentanedione-1,5-calcium disulfonate; and2,4-pentanedione-1,5-cesium disulfonate, respectively.

According to still other embodiments, sulfonation of 2,4-pentanedione isachieved using oleum (fuming sulfuric acid) which is commerciallyavailable from numerous sources including DuPont. In still otheralternative embodiments, sulfonation of 2,4-pentanedione is achievedusing a falling film sulfur trioxide sulfonation, equipment for which iscommercially available from sources such as Chemithon Corporation. Instill other embodiments, a 2,4-pentanedione-1,5-disulfonic acid isprepared as described in U.S. Pat. No. 4,987,249 to Sandler, the entiredisclosure of which is hereby incorporated herein by reference, and isconverted to the salt by reaction with a base comprising an alkali metalor an alkaline earth metal as described above. Exemplary bases includebut are not limited to sodium hydroxide, potassium hydroxide, magnesiumhydroxide, barium hydroxide, ammonium hydroxide, calcium hydroxide andcesium hydroxide.

According to still other embodiments described herein, a disulfonatesalt of 2,4-pentanedione is provided. According to one such embodiment,the salt comprises 2,4-pentanedione-1,5-sodium disulfonate. According toanother such embodiment, a disulfonate salt of 2,4-pentanedione has anenvironmentally acceptable toxicity. As used herein, the term“environmentally acceptable toxicity” means that, when tested accordingto procedures that are the same as or equivalent to those set forth bythe OSPAR Guidelines for Completing the Harmonised Offshore ChemicalNotification Format (HOCNF) (References number: 2003-1) that were ineffect on Dec. 31, 2004, the salt is determined to have a toxicity ofgreater than about 10,000 mg/L for an algae (skeletonema costatum), acrustacean (acartia tonsa), a fish (scopthalmus) and a sediment reworker(corophium volutator).

OSPAR is a commission for protection of the marine environment in theNorth-East Atlantic Sea. The HOCNF protocols in effect on Dec. 31, 2004are known to those of ordinary skill in the art, and therefore need notbe detailed herein. Generally, however, the toxicity tests are conductedwith a known number of organisms (e.g., an algae, a crustacean, a fish,and a sediment reworker) in a known amount of water. The test substance,which may be any of the disulfonate salts of 2,4-pentanedione describedherein, is added to the water until the organisms die or becomeincapacitated. The amount of 2,4-pentanedione disulfonate salt requiredto kill or incapacitate half the test population is divided by theamount of water to give mg/L.

According to yet another embodiment, a disulfonate salt of2,4-pentanedione has a “nationally acceptable toxicity.” As used herein,the term “nationally acceptable toxicity” means that when testedaccording to procedures that are the same as or equivalent to those ineffect in a country of interest on Dec. 31, 2004, the salt is determinedto have a toxicity acceptable for use in the areas subject to suchcountry's procedures.

According to one such embodiment, a disulfonate salt of 2,4-pentanedionehas a nationally acceptable toxicity for the United Kingdom. Accordingto this embodiment, the salt would qualify for a gold ranking under thechemical ranking scheme employed in the United Kingdom on Dec. 31, 2004.This chemical ranking scheme uses data established under theprescreening criteria set by the Harmonised Mandatory Control Systemestablished by OSPAR and the CHARM (Chemical Hazard Assessment and RiskManagement) algorithm to assign a hazard quotient to a chemical, whichquotient then correlates with a color on the following color scale (frommost acceptable to least acceptable): gold, silver, white, blue, orangeand purple.

According to another such embodiment, a disulfonate salt of2,4-pentanedione has a nationally acceptable toxicity for Norway.According to this embodiment, the salt would qualify for a yellowranking under the chemical ranking scheme employed in Norway on Dec. 31,2004. Under the Norway ranking scheme, a black ranking indicates thatthe subject ingredient cannot be used in operations in the Norwegiansector of the North Sea, a red ranking indicates that the subjectingredient can only be used for a certain period of time in theNorwegian sector of the North Sea, and a yellow ranking indicates thatthe subject ingredient is acceptable for most operations in theNorwegian sector of the North Sea. The Norway ranking scheme also usesdata established under the Harmonised Mandatory Control System, forexample the BODIS (Biological Oxygen Demand of Insoluble Substance) andlog P_(ow) (log of the octanol-water partition coefficient) values ofthe subject ingredient. OSPAR, the Harmonised Mandatory Control System,the CHARM algorithm, and the ranking schemes of OSPAR member countriessuch as the United Kingdom and Norway, and techniques for evaluating achemical according to such systems and schemes, are known to those ofordinary skill in the art.

A 2,4-pentanedione disulfonate salt as described herein has a variety ofuses, one of which is as an ingredient in cement compositions. Thus,cement compositions comprising cementitious material, mixing fluid and adisulfonate salt of 2,4-pentanedione are described herein. Such cementcompositions can include any of a variety of cementitious materials,including but not limited to hydraulic cements. Hydraulic cements setand harden by reaction with water, and include Portland cements,pozzolan cements, gypsum cements, aluminous cements, silica cements, andalkaline cements. According to certain of the present embodiments, thecementitious material comprises at least one API Portland cement. Asused herein, the term “API Portland cement” means any cement of the typedefined and described in API Specification 10, 5th Edition, Jul. 1,1990, of the American Petroleum Institute, which includes Classes A, B,C, G, and H. According to certain examples disclosed herein, thecementitious material comprises any of Classes G and H cement. Thepreferred amount of cementitious material is understandably dependent onthe cementing operation.

According to certain embodiments, the 2,4-pentanedione disulfonate saltincluded in a cement composition is selected from the group consistingof 2,4-pentanedione-1,5-sodium disulfonate;2,4-pentanedione-1,5-potassium disulfonate;2,4-pentanedione-1,5-magnesium disulfonate; 2,4-pentanedione-1,5-bariumdisulfonate; 2,4-pentanedione- 1,5-ammonium disulfonate;2,4-pentanedione-1,5-calcium disulfonate; and2,4-pentanedione-1,5-cesium disulfonate.

The 2,4-pentanedione disulfonate salt can be mixed with the cementitiousmaterial as a dry ingredient, or can be mixed with the cementitiousmaterial as a solution. The amount of 2,4-pentanedione disulfonate saltto include in a cement composition depends upon the application to bemade with the cement composition. However, according to one embodiment,a disulfonate salt of 2,4-pentanedione is present in a cementcomposition in an amount effective to reduce the apparent viscosity ofthe cement composition. Thus, a disulfonate salt of 2,4-pentanedione asdescribed herein is suitable for use as a dispersant. According to otherembodiments, a disulfonate salt of 2,4-pentanedione is present in acement composition in an amount of from about 0.01% to about 5% byweight of the cementitious material. According to still otherembodiments, a disulfonate salt of 2,4-pentanedione is present in acement composition in an amount of from about 0.1% to about 4% or fromabout 0.1% to about 3% by weight of the cementitious material in thecomposition.

According to certain examples of cement compositions illustrated herein,the mixing fluid comprises water. Preferably, the water is present in anamount sufficient to make a slurry of a desired density from a mixcomprising cementitious material and a disulfonate salt of2,4-pentanedione. The water used to form a slurry can be fresh water,unsaturated salt solution, including brines and seawater, and saturatedsalt solution. Generally, any type of water can be used, provided thatit does not contain an excess of compounds known to those of ordinaryskill in the art to adversely affect properties of the cementcomposition. According to one embodiment, the water is present in anamount of about 20% to about 200% by weight of the cementitiousmaterial. According to other embodiments, water is present in an amountof from about 25% to about 150%, about 30% to about 100%, or about 30%to about 70% by weight of the cementitious material.

According to still other exemplary cement compositions, any of a varietyof additives known to those of ordinary skill in the art may beincluded. Such additives may include density modifying materials (e.g.,silica flour, sodium silicate, microfine sand, iron oxides and manganeseoxides), dispersing agents, retarding agents, accelerating agents, fluidloss control agents, strength retrogression control agents, defoamingagents, gas migration agents, flow enhancing agents, surfactants, andviscosifying agents.

The following examples are illustrative of the foregoing methods andcompositions.

EXAMPLE 1

A disulfonate salt of 2,4-pentanedione was prepared by first adding575.7 ml (1009.2 g, 8.66 mol) of chlorosulfonic acid to about 1 L ofchloroform in a 3 L round bottom flask equipped with a nitrogen adapterto maintain an inert atmosphere, a water condenser (to minimizechloroform evaporation), and another nitrogen adapter to vent liberatedgases.

The resulting solution was cooled to 0° C., and 403.8ml (393.7 g, 3.93mol) of 2,4-pentanedione was slowly added via a pressure-equalized slowaddition funnel. The solution was stirred and maintained at 0° C.throughout the addition process. After completing the addition of the2,4-pentanedione, the temperature of the solution was raised to 60° C.,and the solution was stirred overnight.

During the temperature increase, hydrochloric acid was liberated and wasvented into a fume hood. After the hydrochloric acid evolution ceased,the reaction mixture was stirred while slowly cooling to roomtemperature. The resulting dark red viscous liquid was quenched withabout 1 L of water and separated from the chloroform via a separatoryfunnel to result in an acid product that included2,4-pentanedione-1,5-disulfonic acid, hydrochloric and sulfuric acids.The acid product was then neutralized to a pH of about 7, which resultedin the formation of 2,4-pentanedione-1,5-sodium disulfonate. Theneutralization was performed by slowly adding 314.4 grams (about 2 molarequivalents of the 2,4-pentanedione-1,5-disulfonic acid ) of sodiumhydroxide under atmospheric conditions. The reaction is extremelyexothermic, therefore the sodium hydroxide was added slowly so thatatmospheric conditions could be maintained. The hydrochloric andsulfuric acid by-products can be neutralized into NaCl (from thehydrochloric acid) and Na₂SO₄ (from the sulfuric acid) with additionalsodium hydroxide.

The neutralized product was then rinsed several times with methanol toremove by-product acids, or any salts formed therefrom, while leavingthe 2,4-pentanedione-1,5-sodium disulfonate primarily undissolved. Whencompared to the 2,4-pentanedione-1,5-disulfonic free acid, the2,4-pentanedione-1,5-disulfonic salt was significantly less soluble,which was unexpected because with many substances, like aromatic salts,the salt is more soluble than the free acid. The rinsed product wasdried in a vacuum oven and filtered through a 300 mesh screen to afforda flowing pale orange/red powder. The resulting powder was2,4-pentanedione-1,5-sodium disulfonate.

The particular amounts recited in this Example 1 are illustrative only,as amounts other than those recited above can be used to render molarratios of reaction and/or neutralization ingredients suitable forpreparing a disulfonate salt of 2,4-pentanedione as disclosed herein.

EXAMPLE 2

Example 2 illustrates an exemplary use for a 2,4-pentanedionedisulfonate salt. While the salt has other utilities, this Example 2illustrates use of the salt as a dispersant in cement compositions.

Sixteen cement compositions (Composition Nos. 1-16) and certainproperties of such compositions are described in Table 1. Each of thecompositions was prepared from a base of 100% cementitious material. Thecementitious material for Composition Nos. 1-12 and 15-16 was API ClassG cement obtained from Dyckerhoff AG. The cementitious material forComposition No. 13 was API Class H cement obtained from LaFarge Corp.'sJoppa plant in Illinois. The cementitious material for Composition No.14 was API Class H cement obtained from Texas Industries, Inc. (“TXI”).

A dispersant and other additives (where indicated) were added to thebase of each cement composition (i.e., to the cementitious material) inthe amounts reported in Table 1, where “% bwoc” indicates a weightpercentage by total weight of the cementitious material.

Dispersant Type A used for Composition Nos. 1, 5, 7, 10, 11 and 13-16comprised a disulfonate salt of 2,4-pentanedione as a dispersant. The2,4-pentanedione disulfonate salt used for the compositions of Example 2was 2,4-pentanedione-1,5 sodium disulfonate prepared according toExample 1, however, a 2,4-pentanedione disulfonate salt can be obtainedby other methods as discussed herein.

Dispersant Type B used for Composition Nos. 2, 6 and 8 comprised acondensation product of formaldehyde, acetone and a sulfite, which is aknown dispersant commercially available under the tradename CFR-3™ fromHalliburton Energy Services, Duncan, Okla.

Dispersant Type C used for Composition Nos. 3 and 9 comprised a phenolichydroxyl group blocked alkali metal lignosulfonate, which is a knowndispersant commercially available under the tradename CFR-5™ fromHalliburton Energy Services, Duncan, Okla.

Composition Nos. 4 and 12 did not include a dispersant.

Other Additive Type D, used for Composition Nos. 1-3, comprised agrafted lignin as a retarder, which is commercially available under thetradename FDP601™ from Halliburton Energy Services, Duncan, Okla.

Other Additive Type E indicates a group of additives, each availablefrom Halliburton Energy Services, Duncan, Okla., that were used to formComposition Nos. 7-9. The additives indicated by Type E according to theembodiments illustrated by Composition Nos. 7-9 comprised: 0.5% bwoc ofa gas migration agent comprising silica, which is available under thetradename Gascon™; 1.1% bwoc of a retarder comprising a refinedlignosulfate, which is available under the tradename HR-5L™; 0.2% bwocof a defoaming agent comprising a seed oil and surfactants, which isavailable under the tradename NF-6™; 0.1% bwoc of a flow enhancing agentcomprising a silica supported acid, which is commercially availableunder the tradename EZFlo™; 5.5% bwoc of a fluid loss agent comprising acellulose, which is commercially available under the tradename Halad613™; and 2.2% bwoc of a fluid loss agent comprising a grafted acrylicpolymer, which is commercially available under the tradename Halad 600™.Each additive in the group of additives indicated by the designation “E”was mixed with the cement, dispersant, and mixing fluid to formComposition Nos. 10-12.

Other Additive Type F, used for Composition Nos. 10-11, comprised arefined lignosulfonate, which is commercially available as a retarderunder the tradename HR-5 from Halliburton Energy Services, Duncan, Okla.

The procedure followed for preparing each cement composition with thecementitious materials, dispersant, additives and mixing fluid asdescribed above was API Specification RP 1 OB, 22nd Edition, 1997, ofthe American Petroleum Institute, which is a specification known tothose of ordinary skill in the art. Generally, according to saidspecification, the cementitious material, dispersant and other additive(where applicable) were dry-blended (the “dry blend”) and then addedover a 15 second period to mixing fluid being maintained in a blender at4000 RPM. When all of the dry blend was added to the mixing fluid, acover was placed on the blender and mixing was continued at about 12,000RPM for about 35 seconds. For each cement composition, the mixing fluidcomprised water in the amount as listed in Table 1, where “% bwoc”indicates a weight percentage by total weight of the cementitiousmaterial. The density (lb/gal) of each composition is reported in Table1.

The plastic viscosity (“PV”), yield point (“YP”) and thickening time(“TT”) were also tested for the compositions indicated in Table 1, atthe test temperatures indicated in Table 1. Each of the plasticviscosity, yield point and thickening time was tested (where indicated)according to procedures well known to those of ordinary skill in theart, and which are described in API Specification RP 10B, 22nd Edition,1997, of the American Petroleum Institute. In Table 1, the results ofthe PV tests are reported in centipoises and the results of the YP testsare reported in Pascals. The results of the TT tests are reported intime (hours:minutes) that it took the composition to attain 100 Beardenunits of consistency (BC) in a high pressure consistometer, determinedas described in API Specification RP 10B referenced above. TABLE 1 OtherDispersant Additive Mixing Type and Type and Test Fluid Amount AmountDensity Temp PV YP TT No. (% bwoc) (% bwoc) (% bwoc) (lb/gal) (° F.)(cp) (Pascal) Hrs:Mins 1 35 A D 16.92 80 96 8.2 not tested 0.2 0.1 2 35B D 16.92 80 89 1 not tested 0.2 0.1 3 35 C D 16.92 80 127.4 7.4 nottested 0.2 0.1 4 41.80 none none 16.14 80 55 11 3:28 5 41.80 A none16.10 80 31 6 5:19 0.684 6 41.80 B none 16.10 80 settle settle 8:380.684 7 41.80 A E 14.99 122 35.6 2 5:15 0.684 8 41.80 B E 14.99 122 45.40 7:30 0.684 9 41.80 C E 14.99 122 46.7 0 9:07 0.684 10 41.80 A F 16.09122 34.9 9.8 3:02 0.684 0.15 11 41.80 A F 16.09 122 27.8 11.3 2:50 0.6840.11 12 41.80 none none 16.14 122 not not tested 2:01 tested 13 32 Anone 17.31 80 44.8 5.9 not tested 0.45 14 29 A none 17.75 80 200 10 nottested 0.50 15 41.80 A none 16.10 122 65 16.9 2:38 0.684 16 41.80 A none16.10 122 66.4 11.8 2:29 0.684

Those of ordinary skill in the art understand that the presence of adispersant in a cement composition affects the PV of the composition, aswell as the YP. PV and YP indicate rheological properties of a cementcomposition, where PV is related to the mechanical friction betweenparticles and YP is related to the force required to break interactivebonds between particles and then to produce movement. In any givenapplication, it may be desirable to increase or decrease the PV or theYP of a cement composition to achieve rheological properties suitablefor that application. Those of ordinary skill in the art understand thata desirable value for either PV or YP depends on the application (forexample, the type of cementing being performed and the conditions underwhich the cementing will occur) being made with the cement composition.Generally, however, those of ordinary skill in the art understand thatthe thickness of a cement composition varies in direct relationship tothe PV value of the cement composition. Cement compositions that are toothick for a given application have flowability problems. Thus, adesirable PV for a cement composition is one that, for a givenapplication, is low enough to avoid flowability problems, but highenough to provide the cement composition with the desired rheologicalproperty for the given application. As to YP, those of ordinary skill inthe art understand that, generally, the lower the YP of cementcomposition, the more likely it is that the constituents of thecomposition will settle out. Thus, a desirable YP is one that is highenough to prevent settling, but low enough to provide the cementcomposition with the desired Theological property for the givenapplication.

Considering that a desirable value for either PV or YP depends on theapplication being made with the cement composition, the PV and YP datafor Composition Nos. 1, 5, 7, 10, 11 and 13-16 illustrate that cementcompositions that include a dispersant comprising a disulfonate salt of2,4-pentanedione exhibit favorable Theological properties as compared tocement compositions comprising conventional dispersants (i.e.,Composition Nos. 2, 3, 6, 8 and 9.)

In particular, a comparison between Composition Nos. 1-3, each of whichcomprised a different Dispersant Type, in equal amounts respectively,and the same Other Additive Type amount, in equal amounts, shows thatComposition No. 1 (which comprised a disulfonate salt of2,4-pentanedione and Additive Type D) has a PV value less than that ofComposition No. 3 (which comprised CFR-5™ dispersant and Additive TypeD), but a YP value greater than that of No. 3, thus making CompositionNo. 1 a more suitable cement composition for certain applications. Asbetween Composition No. 2 (which comprised CFR-3™ dispersant andAdditive Type D) and Composition No. 1, Composition No. 1 has a greaterPV and larger YP value, thus making Composition No. 1 a more suitablecement composition for certain applications.

Composition No. 4, which included only water and cement, provides acontrol for comparison of compositions that included water, cement, andone of Dispersant Types A, B and C, such as Compositions Nos. 5 and 6.For example, a comparison between the PV, YP and TT values ofComposition Nos. 4, 5 and 6 illustrates that cement compositions thatinclude a disulfonate salt of 2,4-pentanedione (Dispersant Type A) haveTheological properties and thickening times that make them more suitablefor certain applications than cement compositions that do not include adisulfonate salt of 2,4-pentanedione (Composition No. 4), or thatinclude a different Dispersant Type (Composition No. 6).

Further, Composition Nos. 5 and 6 are useful for comparing cementcompositions that include, respectively, a disulfonate salt of2,4-pentanedione as a dispersant (Dispersant Type A) and a conventionaldispersing agent (Dispersant Type B), in equal amounts. The PV and YPdata indicate that Composition No. 5 did not settle, while CompositionNo. 6 did. Those of ordinary skill in the art understand that settlingis an undesirable occurrence for a cement composition. Thus, the PV andYP data indicate that a dispersant comprising a disulfonate salt of2,4-pentanedione (Dispersant Type A) contributes favorable rheologicalproperties to a cement composition. Moreover, the TT of Composition No.5 was approximately 3 hours less than that of Composition No. 6. Ashorter TT is desirable in certain cement applications, thus making acement composition such as Composition No. 5 more suitable for certainapplications.

Composition Nos. 7-9 illustrate compositions comprising the same typeand amount of Other Additive (Type E), but equal amounts of differentDispersant Types. The PV and YP data indicate that Composition No. 8(which comprised CFR-3™ dispersant and Additive Type E) exhibits PV andYP properties substantially similar to that of Composition No. 9 (whichcomprised CFR-5™ dispersant and Additive Type E). Composition No. 7,however, (which comprised a disulfonate salt of 2,4-pentanedione andAdditive Type E) has a lower PV value, but a larger YP value, thusmaking Composition No. 7 more suitable than Composition Nos. 8 and 9 forcertain applications. Moreover, the TT of Composition No. 7 was shorterthan that of Composition Nos. 8 and 9, which makes a cement compositionsuch as Composition No. 7 more suitable for applications where it isdesirable to have a shorter TT.

Composition Nos. 10-11 illustrate compositions comprising equal amountsof Dispersant Type A (a disulfonate salt of 2,4-pentanedione), butdifferent amounts of Other Additive Type F (a refined lignosulfonateretarder). Composition Nos. 10 and 11 illustrate that conventionalretarders, such as Type F, are effective in cement compositionscomprising a salt of 2,4-pentanedione. Such cement compositions achievefavorable rheological properties as indicated by the reported YP and PVvalues, and the retarder still functions to slow the TT's of suchcompositions.

Thus, the TT's of cement compositions that include a disulfonate salt of2,4-pentanedione can be adjusted with conventional retarders. In anygiven application, it may be desirable to have a longer or shorter TT.The TT of Composition No. 12, which included only water and cement,provides a control for comparison of compositions that includedDispersant Type A, and optionally, retarding agents. For example, the TTof Composition Nos. 10 and 11 (each of which included a retarding agent)is longer than that of Composition No. 12. The TT of Composition Nos. 15and 16 (each of which did not include a retarding agent) is also longerthan that of Composition No. 12, although not as long as CompositionNos. 10 and 11.

Composition Nos. 13-16 illustrate compositions that include adisulfonate salt of 2,4-pentanedione as a dispersant in varying amounts.The PV and YP data for each of these compositions illustrate that thedisulfonate 2,4-pentanedione salt is an effective dispersant in varyingamounts over a broad temperature range. The amount of a disulfonate saltof 2,4-pentanedione to include in a cement composition as a dispersantaccording to the present embodiments depends upon the application to bemade with the cement composition. However, according to one embodiment,a dispersant comprising a disulfonate salt of 2,4-pentanedione ispresent in a cement composition in an amount effective to reduce theapparent viscosity of the cement composition.

EXAMPLE 3

Example 3 illustrates an exemplary use for a 2,4-pentanedionedisulfonate salt as an ingredient in cement compositions required tocomprise ingredients meeting an environmentally acceptable toxicity or anationally acceptable toxicity. A 2,4-pentadionedione disulfonate saltas described herein was determined to have an environmentally acceptabletoxicity and a nationally acceptable toxicity. In particular,2,4-pentanedione-1,5-sodium disulfonate prepared according to Example 1was determined to have a toxicity of greater than about 10,000 mg/L foran algae (skeletonema costatum), a crustacean (acartia tonsa), a fish(scopthalmus) and a sediment reworker (corophium volutator).

In this Example 3, the toxicity results for the skeletonema costatumwere determined according to ISO (International Organization forStandardization) 10253, the protocol for which is known to those ofordinary skill in the art, and is also the protocol required under theabove-referenced HOCNF Guidelines. The toxicity results for the acartiatonsa were determined according to ISO 14669, the protocol for which isknown to those of ordinary skill in the art. The toxicity results forthe scopthalmus and the corophium volutator were determined according toPart B of the OSPAR Protocols on Methods for the Testing of ChemicalsUsed in the Offshore Industry (published by OSPAR in 1995).

A toxicity result of greater than about 10,000 mg/L for the speciestested in this Example 3 indicates that 2,4-pentanedione-1,5-sodiumdisulfonate has a low toxicity such that it would have anenvironmentally acceptable toxicity and/or a nationally acceptabletoxicity in at least one country of interest, for example the UnitedKingdom or Norway. Such toxicity acceptability makes2,4-pentanedione-1,5-sodium disulfonate particularly useful forcompositions required to meet a particular environmental standard. Other2,4-pentanedione disulfonate salts as described herein should also havelow toxicity such that they would have an environmentally acceptabletoxicity and/or a nationally acceptable toxicity in at least one countryof interest.

Other embodiments of the current invention will be apparent to thoseskilled in the art from a consideration of this specification orpractice of the invention disclosed herein. However, the foregoingspecification is considered merely exemplary of the current inventionwith the true scope and spirit of the invention being indicated by thefollowing claims.

1. A cement composition comprising cementitious material, mixing fluidand a disulfonate salt of 2,4-pentanedione.
 2. The cement composition ofclaim 1 wherein the disulfonate salt of 2,4-pentanedione is selectedfrom the group consisting of 2,4-pentanedione-1,5-sodium disulfonate;2,4-pentanedione-1,5-potassium disulfonate;2,4-pentanedione-1,5-magnesium disulfonate; 2,4-pentanedione-1,5-bariumdisulfonate; 2,4-pentanedione-1,5-ammonium disulfonate;2,4-pentanedione-1,5-calcium disulfonate; and2,4-pentanedione-1,5-cesium disulfonate.
 3. The cement composition ofclaim 1 wherein the cementitious material comprises at least one ofPortland cement, pozzolan cement, gypsum cement, aluminous cement,silica cement, and alkaline cement.
 4. The cement composition of claim 3wherein the cementitious material comprises a Portland cement selectedfrom the group consisting of Classes A, B, C, G and H.
 5. The cementcomposition of claim 1 wherein the disulfonate salt of 2,4-pentanedioneis present in an amount effective to reduce the apparent viscosity ofthe cement composition as compared to a cement composition where thedisulfonate salt of 2,4-pentanedione is not present.
 6. The cementcomposition of claim 1 wherein the disulfonate salt of 2,4-pentanedioneis present in an amount of from about 0.01% to about 5% by weight of thecementitious material.
 7. The cement composition of claim 1 wherein thedisulfonate salt of 2,4-pentanedione is present in an amount of fromabout 0.1% to about 4% by weight of the cementitious material.
 8. Thecement composition of claim 1 wherein the disulfonate salt of2,4-pentanedione is present in an amount of from about 0.1% to about 3%by weight of the cementitious material.
 9. The cement composition ofclaim 1 further comprising a density modifying agent, dispersing agent,retarding agent, accelerating agent, fluid loss control strengthretrogression control agent, defoaming agent, gas migration agent, flowenhancing agent, surfactant or viscosifying agent.
 10. The cementcomposition of claim 1 wherein the disulfonate salt of 2,4-pentanedionehas an environmentally acceptable toxicity.
 11. The cement compositionof claim 1 wherein the disulfonate salt of 2,4-pentanedione has anationally acceptable toxicity.
 12. The cement composition of claim 11wherein the disulfonate salt of 2,4-pentanedione qualifies for a goldranking under the chemical ranking scheme employed in the United Kingdomon Dec. 31,
 2004. 13. The cement composition of claim 11 wherein thedisulfonate salt of 2,4-pentanedione qualifies for a yellow rankingunder the chemical ranking scheme employed in Norway on Dec. 31, 2004.14. The cement composition of claim 1 wherein the disulfonate salt of2,4-pentanedione is mixed with the cementitious material as one of a dryingredient and a solution.
 15. The cement composition of claim 1 whereinthe mixing fluid comprises water selected from the group consisting offresh water, unsaturated salt solution, brines, seawater and saturatedsalt solutions.
 16. The cement composition of claim 1 wherein the mixingfluid is present in an amount selected from the group consisting ofabout 20% to about 200% by weight of the cementitious material, about25% to about 150% by weight of the cementitious material, about 30% toabout 100% by weight of the cementitious material, and about 30% toabout 70% by weight of the cementitious material.
 17. A cementcomposition comprising cementitious material, mixing fluid and adisulfonate salt of 2,4-pentanedione, wherein the disulfonate salt of2,4-pentanedione is selected from the group consisting of2,4-pentanedione-1,5-sodium disulfonate; 2,4-pentanedione-1,5-potassiumdisulfonate; 2,4-pentanedione-1,5-magnesium disulfonate;2,4-pentanedione-1,5-barium disulfonate; 2,4-pentanedione-1,5-ammoniumdisulfonate; 2,4-pentanedione-1,5-calcium disulfonate; and2,4-pentanedione-1,5-cesium disulfonate, and is present in an amount offrom about 0.01% to about 5% by weight of the cementitious material. 18.The cement composition of claim 17 wherein the disulfonate salt of2,4-pentanedione is 2,4-pentanedione-1,5-sodium disulfonate.
 19. Thecement composition of claim 17 wherein the cementitious materialcomprises at least one of Portland cement, pozzolan cement, gypsumcement, aluminous cement, silica cement, and alkaline cement.
 20. Thecement composition of claim 17 wherein the disulfonate salt of2,4-pentanedione is present in an amount of from about
 0. 1% to about 4%by weight of the cementitious material.
 21. The cement composition ofclaim 17 wherein the disulfonate salt of 2,4-pentanedione is present inan amount of from about 0.1% to about 3% by weight of the cementitiousmaterial.
 22. The cement composition of claim 17 further comprising adensity modifying agent, dispersing agent, retarding agent, acceleratingagent, fluid loss control strength retrogression control agent,defoaming agent, gas migration agent, flow enhancing agent, surfactantor viscosifying agent.
 23. The cement composition of claim 17 whereinthe disulfonate salt of 2,4-pentanedione has at least one of anenvironmentally acceptable toxicity and a nationally acceptabletoxicity.